woocommerce_get_page_id deprecated

The normal WordPress file at: /wp-includes/functions.php, line 3831 would not generate that message. Its not a WooCommerce file. So you have a different or corrupted file there. Perhaps you or your developer edited by mistake, confusing it for your theme’s functions.php. This has the same name but it is in a different place: /wp-content/themes/your-theme-name/functions.php

Something’s gone wrong. Try to take a backup before proceeding.

You should be able to reinstall WordPress at
Dashboard > Updates > “If you need to re-install version 4.8–en_GB, you can do so here” > “Reinstall now”.

Thankyou very much for your answer, I went back to the backup I did before, I updated woocommerce once again I got again the same message.
I better leave it outdated… for now.

Its WordPress you need to reinstall.

I will do it, thanks, then I’ll tell you. thanks for your time.

In a clean wordpress installation I copied the woocommerce (outdated) plugin from the backup files, I updated it and I didnt get the message, then I overwrote just the files of the uploads folder and the theme with the files from the backup and then imported the database, then i got again the message. ??